Tag: diseases

If you look back or have been following me- you realize I talk a lot about oak trees and oak wilt. Well that is because it is important-enough said! I was asked to write a “How to” article for a newsletter here in Minnesota. I was given many suggestions that were good, but not up to Kylee quality. There were ideas like how to bud cap, hot to prune, how to develop a sugar-bush….while all good topics, it just didn’t get that fire going in my mind. So after careful consideration, I decided let’s talk OAKS! I decided the article was very informational, so I am going to just paste it here for some good light reading 😉 This is applicable to the Midwest region.

Standing tall with branches reaching out wide and high in the sky stands a strong oak tree in the landscape. Like most things in life there comes a time where this oak no longer looks healthy, and in Minnesota we have a few things that affect our oaks besides old age.

In Minnesota we have a number of different oak species: taxonomically we split them into the red oak family and the white oak family. Red oaks are bristle-tipped leaves and white oaks lack bristle-tips and are rounded. There are many pests and diseases that produce similar symptoms in oaks, so how do we determine what is happening to our oaks?

The first disease to show in the growing season is anthracnose. Anthracnose affects both read and white oaks as well as other tree species. It is caused by a group of fungal pathogens that all cause similar leaf symptoms. Anthracnose occurs when there is a very wet spring. Oaks with anthracnose will have leaves that develop brown spots and blotches, and many times these brown blotches greatly distort leaf shape. Oaks with anthracnose will usually display the most severe symptoms at the bottom and inner parts of the tree canopy. The fungal pathogen will over-winter on leaves and twigs. This disease is not typically the cause of death of oaks, but depending on the percent defoliation and stress caused, other problems such as twolined chestnut borer and Armillaria root disease may attack the trees.

Bur oak blight (BOB) is very similar to anthracnose in that it is caused by a fungal leaf pathogen and symptoms start in the lower and inner canopy. It differ from anthracnose in that it only infects bur oaks, symptoms first appear in mid-summer rather than spring, and it seemingly is causing significant stress amongst some bur oaks in certain parts of the state. Leaf symptoms on BOB-infected bur oaks are first visible as brown flecking along leaf veins, typically seen in July. Later in the summer, abundant leaf drop can occur, starting in the inner canopy, as well as leaves that develop wedge-shaped brown areas. Some dead leaves persist in the canopy throughout the winter, and these serve as the infection source in the following spring. Many citizens mistakenly cut down their bur oaks that had severe BOB because they think they will die: bur oaks with BOB typically re-leaf the following spring, and they look healthy until mid-summer, when BOB symptoms start to develop. Bur oaks can tolerate many consecutive years of moderate BOB before they become susceptible to other problems.

Oak wilt is a xylem blocking fungal disease that shows signs and symptoms throughout the growing season. Oak wilt starts to show symptoms of browning wilting leaves at the top of the crown and moves down the tree from the outside in. Oak wilt affects both red and white oaks. It will kill a red oak in about one month, a bur oak in 1-7 years, and a white oak in 1-20 yeas. Another indicator of oak wilt is the discolored streaking of the sapwood by the fungus. This can be seen by slicing away the bark on an actively wilting branch. Streaking is more readily seen on white and bur oaks than on red oaks. Come spring, if red oaks are not leafing out, examine the tree for subtle cracks in the bark and peel back the bark to reveal any spore pad/ spore mats that the oak wilt fungus sometimes produces. Bur oaks rarely form spore pads, and white oaks do not form them. In order to really determine oak wilt, lab tests of branches are needed, unless a pressure pad is located. Oak wilt is creeping northward in Minnesota and is a highly preventable, yet devastating disease. Please contact your local DNR forest health specialist if you see oak wilt symptoms in northern Minnesota.

Finally, there are other stress-related problems that occur to oaks. When any tree, including oaks, becomes stressed by weather or defoliating diseases/insects it weakens the trees, sometimes allowing for opportunistic fungi or insects to invade. Twolined chestnut borer and Armillaria root disease are examples of these opportunistic pests. Twolined chestnut borer tunnels in the cambium and outer sapwood, eventually cutting off nutrients and water flow through the tree. Armillaria also kills cambium and outer sapwood. When twolined chestnut borer infests an oak, leaves develop a red-brown scorched look from mid – late summer on the top half, or so, of the tree. Twolined chestnut borer typically kill a stressed oak in 1-3 years. The beetle creates small D- shaped holes in the trunk of the tree. When Armillaria is infecting an oak’s root system, leaves in the outer canopy may be stunted and yellow, and branches die back. Over the course of several years, Armillaria root infection will kill a stressed oak. These stressed-related problems are not treatable, but increasing tree vigor with careful harvesting and removal of poor trees can minimize these problems. Harvesting in stressed oak stands should only occur after at least two consecutive growing seasons with near-normal precipitation and no defoliation.

All these insect and diseases are unique in their own ways but have a common target of oak trees and cause somewhat similar symptoms. With a few key distinctions you can narrow down the search! The U.S.F.S. publication How to Recognize Common Diseases of Oaks may help you in diagnosing what is wrong with your oak: http://www.na.fs.fed.us/pubs/howtos/HowToRecognizeCommonDiseasesOaks.pdf.

Leaf drop and branch death from top-down is typically oak wilt, Armillaria, or twolined chestnut borer; leaf death from the bottom up in the spring is typically anthracnose; and leaf death from the bottom-up in bur oaks in later summer is typically bur oak blight!

I do not discriminate against age, size, or strength; I will attack any red oak and kill it. -Oak Wilt

Back in April I knew I would be doing some outreach for oak wilt and needing to research it more extensively in order to help out a few of my landowners and answer questions. However, I never did expect what has happened. I had written a couple overview articles on oak wilt for the local papers just to get the word out there to stop pruning their oaks, do not injure or cut oaks from the time of April- July 15th. Immediately after the news releases the phone calls and emails came flooding in. All leveled off and I began to settle down for a little bit. Most of those calls were just folks who had trees die last year. Now, when I say a little bit I meant it. Soon after that the newly infected trees started to “flag” show signs of wilting. Oh my goodness, I had no idea what I was in for. One of my counties is heavily covered with oak wilt, controlling this and stop it from spreading to the surround counties is key- but is it ideal?! Anyways, LOOOONG story short my new job is Oak Wilt! It is widespread, depressing and hard to control. I say depressing because once infected- tree is dead- too many dead beautiful oaks!!!!!

A couple weeks ago, I got to enjoy a one on one training with one of the oak wilt guru’s in Michigan. I set up a property where I was pretty sure it was oak wilt and so was he. We showed up at my landowners property- hatches in hand and started banging on the the dead trees. First, we were looking for cracks in the the bark, then would test with the hatchet to see if it was hollow. If yes, you start going at the trunk of the tree with the hatchet taking off the bark and revealing this dark football shaped “pressure pad”. The pressure pad forms the following spring after the tree has flagged and kicked the bucket! It often will have a sweet smell attracting the beetles. The pressure pad and its nasty spores are the last fighting chance for the disease to spread! Anyways, back to my experience with the oak wilt guru, enough about pressure pads! After we located the pressure pads, we knew 100% it was oak wilt- that is the sure fire way to diagnose the site as oak wilt. After that, we moved onto looking at a flagging tree. We cut off a branch that had some healthy leaves left as well as some wilted ones. Inside you could see a black ring around outer layer, the cambium. This is the fungus clogging up the water vessels of the branches and trunk.

This is a deadly and relatively fast spreading disease. It is hard to manage at a large scale and costly at small and large scale. The best thing to do is preventive measures. Do not prune or injure oaks during the critical period of April-July 15th and never move firewood! As I sit here and type that, I cannot help but giggle- the movement of firewood is still going to happen. A fallen tree could be in the forest and someone goes and cuts it for firewood and never stop to think oh, why is this tree dead in the first place- and transfers the disease wherever that wood goes…

In Michigan the Conservation Districts, DNR, and MSUE are all working together to GPS track and try to fight this or least slow the spread.

“My lawn looks like fall- I have oak wilt.” …….sigh

This tree is “flagging” turning brown from the leaves wilting from lack of water.Pressure “spore” pad of Oak WiltPressure PadsWater vessels are clogged with fungus (black outer ring)Death Valley- all dead- no discrimination (live trees are red pine, no oak spared)

Vroom, Vroom… I was driving along down all the dirt roads and finally pulled up to my destination. I got out of the car and the gentleman laughed and said so you’re a packer fan! I smiled and said you bet! Then the landowners wife came out to greet me, both so ecstatic to meet me, so gosh darn excited to look at their dying trees. My original reason for the visit was to look at a few oaks they suspected were dead from oak wilt.

First we looked at a white pine, infected with weevil-displaying signs of whats called a shepherds crook. The shepherds crook refers to the previous terminal lateral leader on top the tree dies because a new one is growing and taking over. The weevil larvae are laid just below terminal causing it to die and a new one takes over. This is why we see white pines that are not growing straight up but a rather zig-zag formation.

Then we moved on to to some other trees they were worried were going to get diseased like the others on their property…I say other trees because they were calling them spruce trees-I got closer and I said these are not spruces but are balsam fir trees. MINDS BLOWN!! The joy that exuded from the couple put a smile on my face. They asked how I could tell, I explained to them that the needles are softer than a spruce and are flat and cannot be rolled in their fingers as well as pointed out the smoother bark. They were so excited and I responded with “I have never had anyone more excited to hear they had balsams on their property”! I come from a place where balsam fir trees get a bad wrap–on going joke is set the balsam on fire! Not these two! As they are jumping for joy about the balsams they asked me what was growing inside the tree! They pointed out a lovely case of “witches broom” a fungus that grows often on balsam fir trees and blueberry bushes. Its not just a Halloween prop!

Finally we made it back to the oak trees. They walked up to the oaks, expecting devastation. I looked up the tree and browsed the branches and told them its not dead; I see buds! I explained to them that its a red oak and if it was really oak wilt that “killed” their tree last year it would have died no doubt, but this tree and the ones around it were in fact budding. They looked at each other and shared a smile. They said it was the best news they could have gotten. A few thousand dollar problem may have just been resolved by education. They had read my recent article in the paper and took the right steps in talking about it first before spending the money to trench the tree and remove it. Sometimes oaks die due to bugs killing the leaves and causing them to drop-seeming like oak wilt but the next year the tree often comes back.

We then hopped on their golf cart and started speeding through the woods. Now I may have shocked them with the balsam fir, witches broom, and a living oak tree but rarely am I shocked. He began showing me all the trees he had planted. Red pines, white pines, spruces…all with BUD CAPS!!!!! Bud Capping is something I have been trying to explain to folks here in Michigan to help prevent deer from eating off the terminal bud of young saplings, but No one, until now, has heard of it! It is a University of Minnesota thing and that is exactly where he learned it from. I was in complete awe looking around his property seeing white paper stapled on top of all his young trees! Finally we got to our final destination- A HUGE WHITE PINE!!!!! From afar it looked like any other white pine but up close- Oh goodness I was standing under the mother of white pines! The couple hugged the tree trying to see if they could reach each other-they could not!

This is a common line I hear from many landowners as well as my friends. I often walk through landowners woodlots and they start complaining or mentioning areas they do not go to because the mosquitoes are unbearable. My response is a laugh and then I say “well there is a tree, go buy a bat house”! Often I get a puzzled thought and then response of “really”?! Yes, bat houses are not a cure all but they do help reduce the amount of mosquitoes in an area, least a bit. On average one bat can eat up to 7,000 maybe more mosquitoes in a night!!! ONE NIGHT!!! A tiny little bat consumes thousands of mosquitoes for din din in a night!!! That means get a few bats in there and your problem will be reduced.

Put it up and they will come- I say!

Bats are a hot topic right now in the Midwest and probably other areas, as well. I have been doing research on the Northern Long-Eared bat, Myotis septentrionalis, because it has become an issue here and relates to forestry. It could impact the amount of harvesting done during the summer months. The Northern Long-Eared bat is being affected by the white nose syndrome. It is a fungus that affects the nose, ears and wings of a bat during hibernation. The fungus is cold loving fungus so it attacks them during the cold months; hibernation. The fungus hurts their hydration “processes” and they burn more fat then they should therefore when they wake after a long cold winter they often are dehydrated and die. This fungus is killing thousands of bats.

I have been watching webinars and such on the topic of listing the bat on the endangered species list. There is a lot of controversy because of summer harvesting. Bats roost or sleep upside down in hollow trees and if unknown when a tree harvesting takes place the bats well sadly they die. I believe, correct me if I am wrong, the last I heard was that the bats were listed as threatened.

Awareness needs to be addressed with the subject. We as an economy cannot stop harvesting in the summer months, it would cause crashes in production mills with summer wood and cause more to close. But the bats are also important therefore awareness is key here. So when I tell landowners not to just put up a bat house for their benefits of reduction in mosquitoes and other insects but also so they have a safe place to roost where we are able to tell where they are. Bats get a bad wrap, but really they are harmless and like everything else need to be see as a fluffy little creature so we CARE!

See that tree…put up a bat house….or two or three! Build it and they will come!!

So one of my many things I do besides site visits is outreach type things. I have been to a few venues where I have a table or booth and talk about forestry. Today, I was at a farm show in one of my counties I manage and let me tell you it was good but a bit crazy. I was not sure what to expect because in the past these shows were never in any of my counties, but this was! I did not plan this but it happened to work out that this show was right after the day my article on why we should plant trees, had hit the papers. So needless to say I felt kind of like a local celebrity. I had folks coming up to the table asking for me by name or mentioning my article. I got a lot of smiles and introductions walking through the arena not knowing them before hand. Felt pretty neat but at same time very overwhelming. I had one gentleman walk up to me, who I did not know, and say “hey its our forestry celeb”. Awkward!!

Anyhoot, back to the farm show! It was a great experience- I was able to meet lots of new people and talk to a lot of local landowners about the different invasive species and diseases they need to watch out for and be concerned about in our area. It was the perfect time and place to raise awareness for whats coming ahead. I had lots of handouts on Oak wilt, Beech Bark Disease, Asian Longhorned Beetle, and Thousand Cankers Disease. These few handouts do not begin to cover the issues we are facing in the forests or with trees today but they are major alerts that have not destroyed all of our forest yet so to bring it to high attention is key to me and other foresters, to try and keep on top of it. I had many questions about Emerald Ash Borer- folks wanting to know what they can do with their dead standing trees or if I could give them answers to projections on what may happen with the new growth they have from seeds of trees before the death. I have no answers for this and I don’t think many do but I guess for now I say let it grow and when time comes where we can start to see the outcome we will go from there. As far as the dead standing ash, I had a local logger tell me he is still cutting it and if viable using it otherwise its turned into firewood. But because of the damage done by the borer if not taken care of the wood turns punky and loses is value for even firewood quickly. Now I mentioned Asian Longhorned Beetle, this is not in Michigan yet, but I am trying to raise awareness on it when ever I can because it has been spotted in Ohio, just below us so we need to be aware and possibly prepared. If landowners know what to look for hopefully it can be caught early and eradicated and stopped. It affects the maple trees and maple is another huge market in Michigan so we need to know its out there. I always love the looks I get when I tell folks it hits the maples…it allows me to know they care and are listening because the fear and shock is shown all over their faces. This way I know they are listening and are scared with me! Michigan already lost all their ash trees, we do NOT need to lose the maples too. Oak wilt is already spread through most the state and is taking out great quantities of oak trees. Soon there will be nothing less. I remember back in college my disease and insects professor used to say the “forest is dying and dead” no hope in that statement and being out in the field and seeing properties decimated by various things, has me thinking he was onto something!

Number one question asked at this show “what to do with dead ash”.

Just another plug for forestry–plant trees this spring to help preserve our forests.